No.Your choice of monsters is also hampered by having a level disparity of 2 whole levels in your party. The game mechanics are really geared to the party all being the same level.
Your level 2 guys are going to be 1 or 2 points less to hit, 1 or 2 less on all defenses, have 1 less encounter power, 1 less feat, 2 levels worth of hit points less, and 2 levels worth of magic items less (which can put them further away in the to hit and defenses stakes).
Monsters appropiate for your level 4s will eat the 2s up, and monsters appropiate for your level 2s will be much less of a threat to your 4s.
The difference between 1 and 3 is an entire encounter power + a utility.
Not much?
It doesn't matter if it bothers you or not... if the party members are trivial then you're designing an adventure for 3 level 3 characters.
And how did such a level disparity come about anyways?
I actually decided that everyone is always at the highest XP value for my games to prevent exactly this problem. I see no reason to 'punish' players who can't always show up, and encounter balancing is a lot easier. 1-2 levels of difference might not seem much, but I'm planning to work the tiers into my storyline (so the minute they hit level 11 the scale will change), and I really don't envy the level 9 players who are in the same party as a level 11 character.
Draconomicon has a Red Dragon Wyrmling, level 5 elite version of the red, if you took that dragon, added back the presence and added HP it would basically be a level 5 solo monsters, just make the presesnce 2 less to hit.
To you it's not a punishment, but to the player it is. I can tell you from experience that being 1 to 2 levels behind everyone else SUCKS.