boiler pressure

scott01

I have a home with a weil mclain boiler, single pipe steam. My question is , I don't run it very often {this being the second time all season as most of the time I use 2 dv gas stoves which keep the home warm except if unusually cold}. being that I don't run it often when I turn the stat on I will go down the basement to make sure all is well... last season and now both times this year on first startup after a long period turned off it will run and the pressure gage will climb in a few minutes past 10 psi and keep going...I get nervous seeing this and shut it down, wait till pressure levels off and starts dropping, turn unit back on and it will run fine 1-2 psi and will run at that psi. on subsequent cycling it will run fine staying at 1-2 psi . do I have some kind off airlock or some crud built up in the ppipe leading to the pressuretrol? or is this normal on startup after system is dormant..never really paid attention to how gage was reacting previously. thanks in advance Scott