Propane Leak?

Hi all,
Just took my 1976 Coachman Cadet travel trailer out for the first time of the year this weekend and noticed a lingering propane smell in the unit. I did a little research and don't have a leak detector alarm on my unit (Don't worry, I will be installing one. Is coming in the mail.)

We thought it was just the propane fridge "getting itself going" since it was the first time we used it this year. The fridge/freezer stayed cold all weekend so I don't think it was ammonia. I've read somewhere that it could be the smelling agent they put in propane? I have two 50 pound propane tanks that I filled at the start of last season and haven't refilled yet this year.

I was doing some renos putting up some wallboard in the bathroom (next to fridge) but didn't think there was anything propane wise I would have ruptured on the side of the fridge?

I shut the gas off at the end of the weekend and after a 4 hour drive home the smell was very strong in the trailer. Much worse than on the weekend. The smell was never really strong or even concerning otherwise we would have just shut the gas off.

I'm going to trouble shoot the lines tonight, but though I would throw it out to you all to see if you might have any ideas??

Thanks!