Leak in the Overhead Bunk Ceiling

I've got a leak in the overhead bunk ceiling.  I think that either when I was on the roof, or when I moved the motorhome, that the seal on the seam came loose.  I can cover it with a spare tarp that I have and probably get by for a few weeks.

I went to Walmart in Cambridge a few hours ago to try and get a memory foam mattress.  But they didn't have the right size and they wanted $250 for 8 inches.  The master bed only needs 6 inch thick mattress.  So rather than pay $250, I spent $17.99 on some towels.  My plan was to take the overhead cab bunk mattress and move it to the master bed.  But on the way home, I saw that the weather was going to clear up, so I kept it in place, then went on the roof with my hand broom and started sweeping the standing water off of the top.  I waited it out and it looks like it's working.