I don't think its anything to worry about, unless the memory used keeps on increasing or your system runs out of free memory. A reboot would fix it anyway.
svchost.exe is a "Host process for windows services", and you can find out which ones by clicking "go to service(s)" of the specific instance in the process window of task manager.
You will then see the services tab, and all the services wil be highlighted that belong to that process. There may be multiple services, (all with the same PID), you can then if you want stop any of the services.
Mine is on 32% so you aren't doing too bad
The additional memory usage could be due to a service running that wasn't present before, lot of programs use them.
As long as the memory used by it doesn't continue to increase drastically I dont think its anything to worry about.