That's the problem with branded computers. They often lack sufficient cooling to save costs.
The Vostro and XPS series tend to run hot, mainly due to the lack of fan in the front.
I don't think those temps are out of spec but in general it helps to run cooler, especially in the summer when ambient temps can get higher.
PCI slot fans can help, if you have unused slots. The squirrel cage or blower type fans can move some air without adding too much noise.
You can also upgrade the case fan to a higher CFM unit. I have an old XPS and it was very thin but could easily accommodate a 2" thick fan. The air flow out the case was barely noticeable by hand. 80mm fans can vary from 20CFM to 80CFM.