So to understand correctly what you have done:
a) you had (only?) forum on .COM
b) you moved forum to .NET
c) you put store (ecom) on .COM (Where was store before? Was it somewhere else, was it non existent or was it already part of .COM before your changes?)
Never did a 301. I don't think any internal pages show PR...
I think that page-to-page 301 would be wise to do regardless of PR. It re-enforces to Google that these pages have now changed their location. If you have the same URLs apart from the domain name, then this should be an easy redirect to do.
A question: Since you haven't done 301, what currently happens with forum pages on the COM domain? Do they just return 404 or can you actually access the old forum content on .COM domain?
We did this over the last few days.
This means that there is very little time passed since you have made your changes. There are lots of changes for Google to digest (especially if the store on .COM is also new).
My suggestion would be to set up 301 for forum pages from .COM to .NET, ensure that both domains are in the same WMT account and then wait and monitor the situation over the next few weeks. Google should be able to sort it out on its own - as I said, few days is very little time and you have to allow Google to 'understand' what you are doing.
The only thing I have in my source code with the .com is a google adsense search box.
This is one area that I would look into. I know very little about adsense accounts, so perhaps someone with more knowledge could elaborate on this, for example if you are using the same adsense id on the .NET site as it was on .COM site etc..