Is this illegal? Should I report this?

I have a bit of a situation here and was wondering if anyone could give me some insight. I have a very important out-of-state engagement that I must attend on 04/23, which happens to be the day before Easter. I am currently a student who is a part-time associate at JCPenney and I religiously work every Saturday. Knowing this, I have a put in a time-off request for that particular Saturday off multiple times for the past 3 weeks, which is still ample notice beforehand, and yet it continues to get rejected. I finally got in touch with my store manager via phone a little while ago to inquire the reasoning for rejection & to explain the urgency of my request and he proceeded to tell me that it was a "black out" date (which makes no sense because Easter weekend has never been a black-out holiday weekend in the 5 years I have been there). He told me that if he made an exception for me and granted my request then he would have to do it for everyone, which is understanable I guess. But after, he agreed to approve it only if I promised to "do him a favor in return" if ever needed in the future. I was desperate for the day off and agreed to the conditions, but since that phone call I have been feeling extremely uncomfortable and anxious as to what sort of favor he could possibly need from me. Just to throw it out there, he is gay so I know he wasn't implying anything innappropriate/sexual or anything of that nature...but in all seriousness I really don't believe that it is right/moral by any means that I owe him anything for approving a time-off request, I mean I technically could still be scheduled and then call-off that day anyways so what's the difference if I just get the day off to begin with? Would this situation be considered bribery/illegal and do you think it'd be a good idea to report this? I don't want to be living with this anxiety that I owe him a potential favor, yet if I refuse to do it one day, I don't want any sort of retaliation to occur against me for not keeping my end of the bargain, you know? PLEASE HELP! Thanks in advance for any information you may supply me with!