Shouldn't there be ATIS/sign information on sloped up runways?
FAR 91.103 says (emphasis mine):


  § 91.103 Preflight action. Each pilot in command shall, before
  beginning a flight, become familiar with all available information
  concerning that flight. This information must include -
  
  (b) For any flight, runway lengths at airports of intended use, and
  the following takeoff and landing distance information:
  
  (2) For civil aircraft other than those specified in paragraph (b)(1)
  of this section, other reliable information appropriate to the
  aircraft, relating to aircraft performance under expected values of
  airport elevation and runway slope, aircraft gross weight, and wind
  and temperature.


The most "reliable" place to find this information is the FAA Chart Supplement, which says this for KAVX (emphasis mine):


  Rwy 04 final 2,300´ steep 2.1% downslope, Rwy 22 upslope preferred
  ldg. Pilots cannot see acft on opposite ends of rwy due to gradient,
  must announce taking acft rwy on unicom prior to dep.


Any time you see mention of runway slope, you should be aware that something strange (and likely dangerous) is going on there.  Ditto for the cliffs on the diagram, which you are expected to know would create a downdraft on short final.

Since you were legally required to become familiar with this information when you planned a flight there, no additional notice (such as signs or NOTAMs) was required.

If there had been changes to the airport not yet in the CS, there would be NOTAMs for the airport until the next update cycle--and you would be responsible for knowing those as well.  However, with the airport being closed five months for construction in this case, they had plenty of time to get the CS updated before it reopened.