Can you have a normal echo 1 month and two months later have an abnormal one with the only difference bieng a mild rv enlargement? why would this be?

2nd answer: It is possible for echos to change. For instance, one may develop a right ventricular cardiomyopathy during the interval. All diseases have a date of onset. More likely however, the first echo missed it. RV size is hard to judge on a routine echo unless it's marked or the reader is alerted to look for it by other clinical data. The 1st echo should be re-evaluated with this new data.