questions about 125 flexible plan

I got laid off from former company last Feb, where I setup 125 flexible tax saving plan, I checked the account month ago to make sure there is no balance left, but surprisely, there is about a large amount there, ,curiously, I submit the claim, then I feel uncomfortable, and send the email later to cancel the claim, then the online showed declined initially, but recently, I just found there is an extra amount money in my banking account, then I checked the plan account again, found the claim is approved. I did pay more the daycare fee than that amount though, but I didn’t earned the money, obviously, the company continued put the money in the plan account after I leave, what should I do now? Will my perior company contact me about that? is there any legal issue?