prn vs fulltime

I got hired on as prn nurse for a rehab skilled nursin facility. I have worked in the hospital prior just for one year. the other day they offered me a full time position and needed to know if I would take it a few hours later. I thought about it and ended up saying yes. however, I still haven't signed the offer and we haven't talked about it any more. I am still in orientation and now that I'm talking to ppl on the floor, I'm getting worried that I should stay prn. I guess I'm afraid of commitment and like to have control of my own schedule. would it be rude to tell them I've changed my mind? they said they needed to know the day they asked me because they were about to do an interview with someone and I had asked them to let me know if a full time position comes open. I don't know what to do!!
That's sounds strange & lazy that they would want a fast answer just so they wouldn't have to do an interview. Also not nice of them to cancel someones interview at the last minute.Since they didn't followup & didn't discuss salary and such, I'm not sure if it's a bona-fide offer or not. I also wonder about control & commitment issues. I'd suggest sitting down & talking it out with them. Maybe you both can come to an understanding.
thanks for your response. I wasn't clear about the interview in the previous post. I think they still had the interview but might have offered them a different position, probably a prn. things have been turned around with our orientation (state cameIn so it was cancelled for a few days and then the next week te schedule was messed up and the person doing our orientation had to fill in, so we missed those days too.) and since I hadn't been there since monday, me and the hr haven't had any time to go over it.
sorry if I sound jumbled, I'm using my phone to post and thumbs to type. lol
I've been in a similar situation. You can't make everyone happy. It may be a little rude. But, it's more rude to commit to something you don't want to do, then not to follow through with you commitment.Aplogize if needed, but do whats right for your schedule, your needs. It may be difficult, but it has to be done. Employers do whats right for business, and they would let you go, if they had to.