First Couple of Days Plus A Couple of Dilemmas

So I've made it through the first two days of my new job.  And because the universe likes to keep me on my toes each of those days has also included a bonus surprise that is really good but also places me in an awkward situation.

The job is alright.  The training is not very helpful due to the fact that everyone who usually works at this location quit over a two week period. One has agreed to stay on until the end of the month to help get the 2 new hires (so far) trained.  This means that I am on the fast track since they need me to be taking family and kid portraits yesterday to fill in and because they have co-opted several people to cover the store while the newbies are being trained.

I am supposed to be able to solo shoot by next week as well as open and close the store with all the attendant end of day/week paperwork on my own.  So its been a crash course to say the least.  I would say that my co-workers are 50/50 on the likablilty scale but with the stress level being so high its hard to tell what things will be like when the settle down.  Since I don't know which of them I will actually be working with and how much of the attitude is just from stress.

As if that wasn't enough to keep things interesting, I received a call Wednesday afternoon from a company that I had applied to about a month ago looking for a job.  It is a waaaay more interesting and better paying job then the one I have ended up taking out of necessity.  Also, it is a permanent position.

Thus the battle begins.  Is it unethical to go on this interview? No.  Would I feel bad quitting this job if I was offered this better one?  Only slightly.  Would I look forward to moving back to live near this job?  No.  If I go back to school I will have to quit in 3 - 4 months, I would feel guilty leaving a well paying/respected job that quickly.  I decide that since I don't officially know if/when I am going back to school I can be honest at the interview and not feel guilty.

All of which equals, I book the interview and decide to hope for the best.

Having solved that equation the next day decides to through me a new one.  I receive my acceptance to grad school!  This is weeks and weeks earlier then the said I would get it and it appears from the date on the letter that they sent it merely 2 days after receiving my application.  It is good to feel wanted.  After doing a little dance in my car after my family called me with the news it sinks in that I will no longer have my easy out for my interview next week.

So the question becomes:  Is it unethical to not mention my plans to go to grad school in September when on an interview for a position that I know is permanent?

My gut reaction is that it is unethical but I am not sure.  I don't want to screw anyone over.  Especially a company that I really like/wanted to work for.

Anyone else have any ideas?

(P.S.  I'm the only person in the world who can turn a job offer into a negative event.)