I am a pharmacist and after reviewing information on Valtrex I am not toally sure why that sticker was placed on your prescription vial.
Here is information paraphrased from the professional leaflet from Glaxo:
-was not shown to impair feritility or reproduction in rats given 6 times the normal human dose.
-Is a pregnancy catergory B: Which means it shows no increase in birth defects in studies on lab animals and no known increases in birth defects in human fetuses, even though there are no controlled, adequate human studies during pregnancy.
Specifically in Valtrex's case:
-it does not show any increase in birth defects in controlled studies on animals (rats and rabbits) when given amounts that approximate 7-10 times the amount that would cross the human placenta. There are no known increases in human birth defects that are statistically different than the general population in 749 pregnancies with known first trimetser exposure to Valtrex. Although, this small registry is not adequate to evaluate for less common defects to permit reliable conclusion of safety in pregnant women. Should be used only in pregnant women when the potential benefit justifies potential risk to the fetus.
Why they put that sticker on there I am not totally sure. If the pharmacist you spoke to said it involved ttc and genital herpes perhaps they were referring to the fact that genital herpes can be spread even when not expriencing a active breakout of lesions and Valtrex is to be considered in no way a cure for herpes. I am just not sure what this pharmacist was trying to get at. I cannot find information specifically on that issue of genital herpes vs other uses of Valtrex that justify use of that sticker or warning.
Hope this information has been of some use to you. Try not to worry, it seems there is not much potential for any risk to your possible pregnancy.
If I come across any significant information I will let you know.