Not likely, any air should come right out when you turn on your faucets unless there's a blockage somewhere. Here's a couple of quick things you can try; When you took off the aerator, did you let the water run for awhile? was there good water pressure when you took off the aerator? Try it again and see.
If not, then the blockage may be in the cartridge(s). You may have to take cartridge(s) out and clean them one at a time as well. Start with the hot water faucet first. Shut off water to hot faucet supply line, turn faucet on to relief any pressure, take off handle and remove cartridge. An 8 or 10 inch cresent wrench should do it, unscrew it ccw and clean it really good. Tap it on your hand a couple times, run some water over it, look at it really good and make sure all the sediment is out. While you have it out, turn the water on a little trickle to make sure all the sediment is out of the line. If you have a helper, they can hold a cup over the faucet area while you do this so water doesn't shoot up to the ceiling. Otherwise just turn it on a trickle, that should be enough to push out any sediment. While it's trickling out look for any sediment. Any excess water will flow down the drain. Put the cartridge back in, tightened it down, and try it again. Same steps as above - remove aerator let run for awhile - replace aerator. Now do the cold water faucet the same way if needed. There may be pieces of sediment that can't pass through the cartridge(s) or it's trapped in the cartridge(s) somewhere.
If it still trickles then the blockage is elsewhere and will go from there. Let us know how it worked out for you.
When replacing elements or doing any kind of work on the hot water heater, where it's turned off and on and drained, etc.,it always stirs up sediment. Sometimes it gets built up in your aerator or faucet cartdrige and slows down the pressure. Usually you go around and remove/clean the aerators, let the water run a little bit, then put aerators back on like we said up above. That usually fixes it most of the time. However, sometimes you may have to remove a cartridge once in awhile for big pieces of sediment. Just a small piece of sediment can effect the water pressure of that faucet.
When was the last time the water heater was drained and flushed out really good?