Did your HCP do the in-situ audiometry before or after REM? If before REM, then did he/she have Genie 2 represcribe the gain curve to the new in-situ result before doing REM? If your HCP did REM before doing the in-situ audiometry and have Genie 2 re-prescribe the gain curves to the new in-situ result and didn’t do REM again afterward, then all the REM adjustment done prior to the in-situ audiometry will have been lost due to the re-prescription.
That would be a more important question to ask than the vent size being a little bit smaller than the recommended default based on the in-situ result. When/if you gain curves are chosen to be re-prescribed based on the new in-situ result (instead of basing on your original audiogram), as long as you leave your vent selection to its actual size of 1.0mm, then Genie 2 will use this information to re-prescribed properly to this 1.0mm size for you.
The only time you may want to change to the recommended 1.4mm vent is if and only if you feel like the 1.0mm vent size you currently have is too occlusive and you prefer to go bigger to the 1.4mm size and actually take action to do so. Then you need to update that info in Genie 2 and re-prescribe the gain curves based on that new size, then your HCP should rerun REM for you because your fitting has now changed.