Drove through water - concerned about car

What is your question?

We had extremely heavy rains for a few days in a row and a road area that never sees any flooding got some which surprised all of the drivers on the road. I drove through slowly (I am not sure how deep it was - people keep asking but it was hard to judge as it was raining very hard and cars were coming in other direction splashing water as well) my car stalled out suddenly for a second but started right up. as I was almost through again it stalled (I should insert here that I was on my way for gas and I was nearly empty so I thought ran out of gas) I started up and went on my way. The car was NOT making any noise at all and running fine. I stopped for gas and the car started up fine and ran fine again. I made one more stop and started it remotely to see if it started and it did just fine and ran fine. The following morning I went out to drive and, again, started and ran fine. A full day after the incident (over 24 hours) I started the car (had been driving it all day with no problem) and was hearing a high "hum" sound (like when the AC kicks on and off in the car) but it was constant. The next morning I took it to get my oil changed (it was due and someone suggested it to be good idea since I had driven through water) and the mechanic there said it sounded like my AC Compressor Clutch and it probably just needed to dry out. The car is still making the noise a day later (2 1/2 days after I went through the water). It isn't constant and it doesn't get worse with acceleration or anything. The car is still running as well as it did before. I believe they checked all of my fluids when I got my oil changed (I asked them to) I am assuming had I done any damage to the engine I would have known by now. No lights have come on and it runs fine. I am hoping that the noise is coincidence but I am still very stressed and concerned.