How did it get back to you, and how far did it have to travel? I left mine in Hong Kong a few months back, and that damn thing swam all the way to Guam before stowing away on a Navy transport ship to San Francisco, then hitchhiked all the way back to Virginia. Just a knock on the door one night and there it was! Needless to say I was impressed, and while glad to have it back, it never worked quite the same -- I blame the seawater. It is pretty cool that those things will find their way back to you when you lose them though...
On a more serious note, if I were the OP I'd definitely back up anything important on that card, as it may be getting ready to die. If the card is frequently getting disconnected, it's either an issue with the Phone's SDcard slot, or the card itself is becoming corrupted and/or unreadable. In case it's the latter, like I said, I'd get your stuff backed up.