Once you’ve started with a water based sealer it’s best if you stick to the same one. You will find your gates swell and contract naturally since they will absorb atmospheric moisture to a certain extent anyway, especially via the end grains which are seldom properly sealed.
I wouldn’t do anything right now since the gates may contract when the weather is warmer and there is less atmospheric moisture. In the summer do any trimming/planing you need to do and then have another go, making sure you cover every edge and surface. And, always, allow a little bit of leeway for natural movement throughout the year.