Your question is very confusing and I'm not sure anyone really understands what it is you're asking. If you're asking if you change jobs and go from an W2 to 1099 income no one cares as long as you make your mortgage payments. If you're asking if you can get a second loan based on 1099 income that you didn't report on the first loan application relying solely on the reported W2 income, I don't know how anyone on Trulia could answer this without having reviewed your entire file in terms of Income, Assets, Credit scores etc. You need to articulate your question better so that we understand what it is you're really asking.
If you have closed your loan, then it a done deal. If you want to switch jobs, then that's your prerogative. Just make sure you making the best the decision you can. You now have the added responsibility of homeownership.
A 1099 form represents additional non-employee income that could be in addition to a W2. Using a W2 and a 1099 to file taxes is common. Once the bank loan is closed and there was no fraudulent income disclosure, what happens after the loan is immaterial. But, due to the wording of this question, the reasoning behind this decision is unclear.