<p><a href="https://i.stack.imgur.com/rtG5C.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rtG5C.jpg" alt="enter image description here"></a>
<a href="https://i.stack.imgur.com/i1oaO.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/i1oaO.jpg" alt="enter image description here"></a></p>

<p>I'm getting some slight pooling on the end of straight lines on my Ender-3</p>

<p>Is this due to over extruding? Or some other issue?</p>

It's not necessarily the case that the apparent underextrusion of a small portion of your raft is the root cause.  ABS is notorious for shrinkage and peeling.  As a start, you should have a full enclosure so as to maintain a warm environment while printing.
It's also quite possible that your bed is slightly off-level or a few microns low for the first layer, either of which can cause adhesion problems.
Yes, it's pretty much trivial to add a few lines of gcode to extrude prior to the "official" raft -- or you could just toss a fake small object into your slicer to extend the raft over both the real and the fake parts.
FWIW, with a little care I've found a wide brim outperforms a raft for almost anything I print