If you cast Grease on the strands of the Web itself, a DM could reasonably rule that you gain a +10 on escape artist checks to escape the web. It's not specifically stated in the spell, but being caught in a sticky web can be seen as being similar to being grappled.
Or he might not, since it's not a specific benefit of the spell.
However, if you cast Grease on the floor beneath someone who is caught in a web, it becomes a nightmare for them. If they fail their save against the Grease they are prone and restricted to 5' of movement, which makes it very hard to break out of the web. If they make their save against the grease, they have to make a balance check when they try to force their way through the web and possibly become prone that way.
This is really nasty when you use a the Sculpt Spell feat on the Grease spell so that it has the same radius as the Web spell.