Is this a recent development, or was it always like that?
On most bikes, first-second has a greater distance to travel when compared
to the other gears. This is because the selector had to rotate through
neutral before reaching second gear. A few bikes like my Kawasaki
have a mechanism to prevent second gear selection unless the bike
Check clutch adjustment. Is the clutch behaving properly? Clutch
drag caused by a warped plate(s) can cause gear selection problems.
Check the pedal and linkages for dirt or corrosion.
Have you changed oil recently or are you due an oil change?
Using the wrong grade can make a noticeable difference to
Hopefully it is just a minor service issue and not an indication
of wear or damage in the gearbox. What kind of bike is it?
My first thought was oil. Either recently changed or needs changed if this has recently become a problem. Look for the simple things first. Clutch adjustment next. Then the clutch basket. At that point do some searches here because clutch repair has been addressed in pretty good detail as I recall.
It is certainly possible but 25 miles is about the right amount of time for the wrong oil to start causing problems too. I'd confirm you used the correct oil before tearing it apart if it were mine. But that's totally your call.
There are a lot of things which can lead to difficult shifting. The easier things to check are:
Correct type and amount of oil
Clutch cable adjustment correct (if applicable.)
No issues in Hydraulic clutch system (if applicable.)
Shift lever adjustment (move it a notch up or down - sometimes this helps!)
If those are all OK, the harder stuff is:
Worn clutch or throw-out system
Bent or worn shift forks
Worn or broken transmission components.
Some of those things above will generally condemn a bike unless you can score a really good eBay auction and have the time and knowledge to take the trans apart.