Quick update from my earlier post...
My dad checked out my flat tire and said the wheel valve was cracked. He was afraid that was probably the case on all the tires. So the likelihood of having more flat tires was high...so....
I went to a garage and yes indeed...all the tires could have easily gone flat at any time. The valves were cracked on all of them. When I had my new tires put on at Sears 1 1/2 years ago they didn't replace the valves.
The guy at the garage took off one of the front tires, literally touched the valve on the wheel and the air gushed out of the tire.
He said it isn't unusual for many places to leave it up to the customer to decide about replacing the valves, etc when they get new tires. This garage doesn't do that. They add it into the service since most people don't know what all that even means.
Needless to say, I will be giving him my business the next time I need tires. He fixed all of my tires when he was getting ready to close for the day. He was pleasant and had excellent customer service. And he's local.
I'm feeling very grateful today.
Off to get ready to cook dinner for my parents in my new place.