This covers Hondas only, but I'm sure there is one for Acuras too. Acura owner will need to search for this info.

Transmission Grinds When Shifting Into 3rd Gear, Pops Out of 3rd Gear, or
Is Hard to Shift Into 3rd Gear

SYMPTOM
The 6-speed manual transmission grinds when shifting
into 3rd gear, pops out of 3rd gear, or is hard to shift
into 3rd gear.
NOTE: These symptoms can be intermittent and
sometimes more noticeable in colder climates.

PROBABLE CAUSE
The transmission has a faulty 3rd gear synchronizer or
3-4 shift sleeve.
CORRECTIVE ACTION
Replace the 3rd gear set.
VEHICLES AFFECTED
2003–07 Accord V6 with M/T: ALL
2008 Accord V6 with M/T 2-Door:
From VIN 1HGCS218.8A000001
thru 1HGCS218.8A003478
2006–07 Civic Si 2-Door: ALL
2008 Civic Si 2-Door:
From VIN 2HGFG215.8H700001
thru 2HGFG215.8H701973
2007 Civic Si 4-Door: ALL
2008 Civic Si 4-Door:
From VIN 2HGFA555.8H700001
thru 2HGFA555.8H702465


Dealerships Fixing 3rd Gear
List of Dealerships fixing 3rd gear problems - 8th Generation Honda Civic Forum

Click here for a thread with all recalls and TSB's listed

-Frankie