What's the mission pacing set to? If it's flat, you might find a good number of +1 enemies even at lower levels. That's still better than running into +2s and +3s at the end of the level though, with -2s and -1s near the start to add some kind of balance.
It's hard to make missions that are playable at all levels. You'd pretty much have to set all powers to standard for lowbies, but then highbies would get bored. It's a tough situation.
I had it set to staggered then changed it to flat and didn't see any difference, actually. 
I was thinking to just drop a warning note ("For higher levels only" or something), guess I'll have to go with that. I do not what you mean by being bored though; running through it with a 50 or anyone over 40 with good DPS it was mostly a breeze. Which I can live with, really.
I'm having trouble getting my minions to spawn at less than "these guys are tough!" levels. I want my mission to be playable for as close to any level toon as I can, but my minions and lt.s spawn at yellow-con and orange-con respectively even when I'm set at the easiest setting (level 1 difficulty). I'd prefer if they came up white-con/yellow-con at that level. The only time I see white-con though is if I have a group set for "hard" that's surrounding a captive you have to free, then it puts down 2 white-cons and two yellow-cons.
Why does this happen? Does the system look at their power sets and think "these are tough, I'm gonna yellow- and orange-up them" or something? Maybe at the settings for the powersets themselves ("standard", "hard", etc.)?
My minions are Assault Rifle/Force Field (both set at standard) and my Lts. are the same but with AR set at hard if that helps.
Any help in this area would be greatly appreciated.