Maybe and maybe not.  They've matured a lot over the summer, and most of their jealousy had its roots in the rivalry that went on during school, plus the fact that each of them never had a real father figure and were scared to lose him to the "enemy" so to speak.  However, Sarai doesn't live with them, is visiting, and while it is awkward at first and confusing, for Harry especially, to think that his father is actually invovled with a lady, the level of jealousy isn't as high.  Yes, Severus did hug her at first, but he hasn't kissed her at all in front of the boys, the first kiss was shared while they were still outside, and they are being discreet, keeping the PDA's down to looks while the kids are present.  Neither of the boys has ever heard Sev tell Sarai he loves her either, though it is implied, they don't say it that often and if they do it's usually in private. 

However, in the next chapter, Harry will have two separate talks about Sev's relationship, one with his father, and the other with Smidgen, who has her own advice to give, which will help quell some of the anxiousness.  Plus Sarai herself spends a good deal of time with them and helps them smooth over some rough spots with Sev, so they come to regard her as an ally rather than an enemy. 

It could have been different if she moved in with them, but that doesn't happen, and her relationship with Harry & Draco can grow gradually.