Is a test injection needed when UPLC system is idle?

[EmpowersBane]

I use a UPLC binary to run my samples using a 1.7micron, 2.1*100mm column and its a gradient that runs for 45 minutes. I normally run a few condition columns at the start of the run to equilibrate the system but I noticed when I don't use the UPLC for a few weeks then put on a new run, the first 2 or 3 injections have odd retention times and resolutions that normally pass end up failing.
It usually settles out after a few injections but I have failed system suit before and I have to run 1 or 2 trial injections to "settle" the system before injecting a run, is this normal?

[Consumer Products Guy]

I ALWAYS made "test" injections on HPLC and GC each day before starting my sequences.

Notice that I used capital letters.

[Aldijkhuizen]

At what temperature are you working?