I always worry in the same way. when I have neglected my layout for a while I feel the same trepidation that maybe things won't go well, even though, as an engineer I know there is no reason why everything should not go well.
It happened again this past weekend, here. Due to a series surgeries and all that, I had "neglected" my trains for eight weeks. When I went up this past weekend to run them all, I worried. The entire layout was a bit dusty, and the track was dirty. I ran a vacuum cleaner car and then a track cleaning car for half an hour on each loop, while I set up a jig to clean rollers and wheels on the locos I wanted to run. I had no problems. Everything worked perfectly.
This always pleases and surprises me a bit when this happens, and yet when you think about it, why should it? If the layout is well made, there is nothing that should go wrong. In my case I have sold-rail O-Gauge track with every joint soldered, and big wire (#10 or larger) feeders soldered to the rails every ten feet, all run under the layout where they are out of harm's way. The whole room is heated and cooling and kept dry. The power supplies and such are reliable and will last for decades. Barring some critter getting under there and chewing the wires up I can't see anything going wrong there. The locos and such aren't going to deteriorate if left for a few months ((longer than that and I'd oil them and renew the smoke fluid, but . . .). Everything should just sit there and wait - and still work weeks, months, even years later if the tarnish is cleaned off . . .
But it always surprises and delights me when everything does go ell. It guess the eight-year old kid inside me just doesn't complete trust the knowledge the 70-year old enginner has!