Help! propane detector went off now what?

Hello all,

New to the travel trailer world (we had a pop up before) and we just had our first experience with the propane detector. We leave our camper at our river lot until we take it out of town, since we frequent the river every week. This past Wednesday we locked our starcraft bunk house trailer up and didn't make it back out till today. Upon arrival the detector is blaring. We did let the propane tanks open, but what should we do now?

Is this something we need to take it in for service? Or could this have been a random occurrence?

Thank you for your help.