4th edition combat's different than 2nd edition.
In second edition, at first level, your warrior starts with 10 or so hps, but most monsters you fight early on don't hit often, and when they do it's for a small amount, 1, 2 sometimes 3. Those 10 hps, along with the cleric's reserve of Cure Light Wounds, are supposed to last your adventuring day. Monsters at that level have 1/4 or 1/2 hit dice, meaning that you'll face kobolds with one hit point, two if they're extra tough, and the occasional goblin with three. Your warrior is probably killing everything in one blow.
A 4th edition fighter might have around 30 hit points to start... but he's getting hit for 10-20 hit points of damage. Monsters themselves start at 33 hit points, minimum, and will go up from there. Sure, you'll fight a few minions here and there, but most encounters have monsters that take multiple hits to kill. Instead, you probably have 11-14 healing surges that are to last you the entire adventuring day, each of which are worth 8 hps a piece. But because you get for so much harder, death is always a possibility, even if you have healing surges left.
Fourth edition's battles have a swingier hp curve... it goes down and up rapidly, and fights are a little tenser. There's no real mop-up fights, or 'simple' encounters like 2nd edition.